Roll coating apparatus for panel products

ABSTRACT

Roll coating apparatus for coating plywood and other panels comprises coating applicator means and wiping means arranged sequentially for processing the underside of a horizontally positioned panel. The applicator means preferably comprises a roll coater. The wiping means comprises an upper pressure roll, a lower wiping roll, and mounting means mounting the rolls rotatably in axially aligned, cooperating relation a predetermined distance from each other. Wiping roll drive means are connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction. The applicator means applies coating material to the underside of the panel while the wiping means distributes the coating material and wipes off the excess to produce a highly finished surface. The sequence may be applied to panels moving rapidly along a high speed production line.

United States Patent Reeve et a1.

1 1 ROLL COATING APPARATUS FOR PANEL PRODUCTS [72] Inventors: Darrel Lon Reeve; Stanley Mortensen, both of Eugene, Oreg.

[73} Assignee: Georgia-Pacific Corporation, Portland, Oreg.

221 Filed: Aug. 6, 1970 21 App1.No.: 61,587

[52] U.S.Cl. ..ll8/l04,1l8/l12, 118/114 [51] Int. Cl. ..B05b 13/02 [58] Field ofSearch ..118/100, 104, 110, 111,112,

[56] References Cited UNITED STATES PATENTS 662,910 12/1900 Britton ..1 18/224 677,343 7/1901 Delaney ..118/114 2,925,800 2/1960 Wassem ..1 18/1 14 3,532,073 1/1970 Nelson......................118/1l0 2,684,047 7/1954 Walker ..118/121 2,642,030 6/1953 Brink ..118/114 [451 Sept. 26, 1972 FOREIGN PATENTS OR APPLICATIONS 815,666 7/1959 Great Britain ..1 18/1 14 Primary Examiner-Henry S. .laudon Attorney-Eugene D. Farley 57] ABSTRACT R011 coating apparatus for coating plywood and other panels comprises coating applicator means and wiping means arranged sequentially for processing the underside of a horizontally positioned panel. The applicator means preferably comprises a roll coater. The wiping means comprises an upper pressure roll, a lower wiping roll, and mounting means mounting the rolls rotatably in axially aligned, cooperating relation a predetermined distance from each other. Wiping roll drive means are connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction. The applicator means applies coating material to the underside of the panel while the wiping means distributes the coating material and wipes off the excess to produce a highly finished surface. The sequence may be applied to panels moving rapidly along a high speed production line.

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ROLL COATING APPARATUS FOR PANEL PRODUCTS This invention particularly to roll coating apparatus for panel products. It pertains particularly to apparatus applicable for roll coating wood panels, such as plywood, fiberboard, and particle board panels having irregular or embossed surfaces.

In the manufacture of wood panel boards, particularly decorative plywood panelling, it is customary to coat the finished panels with a suitable coating material such as varnish, lacquer, or paint. Roll coating apparatus normally is used for this purpose, since it is well adapted to the application of a coating material to panels traveling at high speed horizontally along a continuous production line. However, the use of such apparatus is attended by troublesome difiiculties. Excess coating material smears the panels. Dust collects on the panels before and after coating and causes surface imperfections. Nails, metal pieces, wood fragments and other scrap materials collect on the panels and tear up the coating rolls. The coaters do not coat efficiently decorative panels having embossed or antiqued surfaces.

It is the general purpose of the present invention to provide roll coating apparatus for panel products which overcomes the foregoing difficulties and which in addition is characterized by the following advantages:

l. is adapted to operation at extremely high production line speeds, i.e. speeds of several thousand panels a day.

2. ls adapted to use with extremely fast drying coating materials, i.e. coating materials which dry in a few seconds.

3. Is adaptablefor use in coating a wide variety of panel products including plywood, particle board and fiberboard.

4. is adapted for use in coating embossed plywood and other products having irregular surfaces.

5. ls useful in the application of a wide variety of pigmented and unpigmented coating materials including paints, varnishes and lacquers.

6. May be included in existing production lines without adding men or altering the lines.

7. ls versatile in that it may be modified to include or exclude supplemental coating units as required by the quality and nature of the work.

8. is subject to precise control of coating thickness.

9. ls subject to precise coating material viscosity control even when using coating materials which dry very rapidly.

10. Is subject to running adjustment.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the accompanying drawings wherein:

FIG. 1 is a view in side elevation of the herein described roll coating apparatus, partly broken away and partly in section;

FIG. 2 is a view in end elevation of the roll coating apparatus, viewed from the infeed end; and

FIG. 3 is a view in side elevation of the roll coating apparatus looking in the direction of the arrows of line 3-3 of FIG. 2.

in its broad aspect, the herein described roll coating apparatus for coating plywood and other panels comprises applicator means and wiping means arranged sequentially for processing the underside of a horizontally positioned panel. The applicator means preferably comprises a roll coater. The wiping means comprises an upper pressure roll, a lower wiping roll, and mounting means mounting the rolls rotatably in axially aligned, cooperating relation a predetermined distance from each other. Wiping roll drive means are connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction. The applicator means applies coating material to the underside of the panel while the wiping means distributes the coating material and wipes off the excess to produce a highly finished surface. The sequence may be applied to panels moving rapidly along a high speed production line.

Since the apparatus coats the underside of the panel, coating imperfections caused by dust specks, refuse accumulations, and glue smearing are overcome. in addition, when coating embossed surfaces, the high surfaces are wiped and the depressions coated with a high degree of efficiency to give desired efiects.

Considering the foregoing in greater detail and with particular reference to the drawings:

The apparatus is supported in a frame consisting basically of a pair of side plates l0, l2 bridged by a plurality of transversely arranged bars 14. The frame is open at its infeed and outfeed ends.

Panels 16 are fed in the infeed end, one at a time, face down. As indicated above, the panels may comprise plain or embossed sheets of plywood, fiberboard, particle board, flake board, etc. The sheets are full sized, measuring in the usual case 4X8 feet, or even more. They traverse the apparatus at a high rate of speed. Thus several thousand panels a day may be coated in a single coating unit.

In its full assembly, the coating unit comprises three coating sub-assemblies applicable individually or in any desired combination. These are indicated generally at 18, 20 and 22 of FIG. 1.

Sub-assembly 18 serves the combined functions of driving the panels through the apparatus and flooding their undersurfaces with coating material.

The panels are guided into subassembly 18 by guide means comprising a pair of angularly bent plates 24 converging in the downstream direction and supported on side plates l0, 12 by means of hangers 26.

Sub-assembly 18 comprises a pair of cooperating rolls: an upper pressure roll 28 with shafts 30 and a lower coating roll 32 with shafts 34.

Pressure roll 28 has a covering 36 of a resilient material, such as durometer rubber, to provide the desired resilient peripheral surface. Roll 32 has a surface coating 38 of a resilient material such as 40 durometer rubber.

The two rolls are arranged in aligned, cooperating relationship and driven in the feed direction by a drive to be described later.

Pressure roll 28 is so mounted that the amount of pressure which it exerts on the work may be varied as desired. To this end, shafts 30 are joumaled in bearings mounted in slides 40, FIG. 3. The slides are received in vertical guideways 42. A post 44 fixed to the upper end A hand operated lever 50 is connected to the upper end of threaded sleeve 46. A coil spring 52 is mounted on the lower end of post 44, and lock nuts 54 on its threaded upper end. Spring 52 bears against the upper end of slide 40 with a pressure determined by the setting of threaded sleeve 46. This in turn determines the pressure exerted by roll 28.

Coating roll 32 is mounted in mounting means adjustable not only to vary the nip between the two rolls but also to remove the coating roll entirely from its operative position, if this should be desired.

For this purpose, each shaft 34 of the coating roll is journaled in a bearing 60 which is supported on a cross bar 62. The cross bar acts as a slide and is mounted for vertical sliding movement on slide 64. Vertical adjustment is provided by means of a jack screw 66 journaled in bearings 68, 70. The lower end of jack screw 66 is threaded and received in a threaded sleeve 72 secured to side plate 12.

Jack The 66 is driven by a drive assembly including a sprocket 74, a crank-operated shaft 76, a crank 77, a sprocket 78 and an interconnecting chain 80. This construction is duplicated on the other side of the apparatus. Hence the elevation of coating roll 32 may be adjusted between predetermined limits of nip by operation of crank 77.

A doctor roll 82 having axially extending shafts 84 is associated with coating roll 32 for applying coating material in controlled amount to the surface of coating roll 32. The doctor roll may be of the usual construction, comprising, for example, heavy steel pipe having its surface machined and highly polished.

Doctor roll 82 is supported on a mounting which permits its adjustment toward and away from the coating roll as required to provide the desired doctoring effect.

To this end, each shaft 84 is mounted in a bearing 86 which in turn is supported on a vertically arranged bar 88. The upper end of the bar is pivoted to one of the frame side plates, e. g., side plate 12 in FIG. 3, by means of a pivot pin 90. The other end of the bar pivotally is connected to the piston rod 92 of a cylinder 94. The case of the cylinder is pivoted to a bracket 96 mounted on one of the side plates. Accordingly adjustment of the cylinder varies the position of doctor roll 82 in the desired manner.

Additional combination feeding and coating roll subassemblies may be included in the combination unit as desired. In the illustrated form of the invention, there is one additional such sub-assembly, i.e., that indicated generally at in FIG. 1. [t is substantially identical in construction to the sub-assembly above described. it functions not only to apply additional coating material to the panels, but also to control the total amount applied thereto. Thus coating assembly 18 may be adjusted to flood the panels with coating material, while coating assembly 20 may be set to meter and control the amount of coating material thus applied.

Both of the coating roll sub-assemblies are supplied with coating material from a pan 100 detachably mounted between side plates 10, 12. The inner end of the pan is supported on studs 102 extending inwardly from the side plates and engaged by clips 104 extending downwardly from the inner end of the pan.

he outer end of the pan is detachably retained in place by means of spring-pressed pins 106 mounted between tabs 108, 110 carried by the pan, and

penetrating aligned openings in side plates l0, l2. Accordingly pan may be removed completely by retracting spring-pressed pins 106 and detaching clips 104 from studs 102.

Pan 100 is filled with the desired coating material. This may be a paint, lacquer, varnish, or other liquid coating material. The elevation of the coating material in the pan is controlled so that the coating material is contacted selectively by doctor rolls 82, which then apply it to coating rolls 32.

The coating material is supplied to the pan by means of an infeed pipe 112, FIG. 2. it is exhausted from the pan by one or the other of outfeed pipes 114, 116. These are arranged at different levels and serve as a depth control. Normally the overflow material is removed through pipe 114. However, if for some reason this should become clogged, the suplus material is removed through pipe 116, preventing overflowing of the pan.

The liquid coating material is circulated at the desired rate by means of a pump, not illustrated, which draws from a reservoir of suitable capacity, pumps the coating material through infeed pipe 112 into pan 100, whence it is returned to the reservoir through one or the other of outfeed pipes 114, 116. Make up material and viscosity controlling agents such as diluents and thinners may be added as desirable or necessary.

Sub-assembly 22 has for its primary function controlling the spread of the material on the coated under surface of the panels, and wiping that surface for the removal of surplus material. This is of particular importance when coating embossed panels in order to give a finished appearance to the embossed surfaces.

This sub-assembly includes an upper pressure roll which may be substantially identical with pressure rolls 28 above described in its construction and mounting. it also includes a cooperating, reversely driven wiping roll rotatably mounted on axially extending shafts 122.

Wiping roll 120 is mounted adjustably in peripheral pressure contact with the work by means of a mounting illustrated in FIG. 3.

Each shaft 122 is journaled in a bearing 124 supported on a slide plate 126. The slide plate in turn slides in a pair of vertically arranged guides 128. It is adjusted by means of a double acting fluid-operated cylinder 130, the piston rod of which pivotally is coupled to the lower end of slide plate 126.

Adjustment of the cylinder upwardly and downwardly correspondingly raises and lowers wiping roll 120. It is maintained in its upper, operative position by means of a lock finger 132 pivotally mounted on a stub shaft 134 and adjustable between an operative position wherein it underlies and supports slide 126 and an inoperative position wherein it is withdrawn therefrom, permitting lowering of the roll.

Back and pinion means are provided for supplying power to the slide assembly on the side of the apparatus, remote from cylinder 130, thereby eliminating the necessity of providing two cylinders.

Slide 126, which is connected to cylinder 130, mounts one end of a rack 136. The other end of the rack is guided by a guide 138. The rack engages a pinion gear keyed to shaft 142 which extends laterally across the apparatus to the far side thereof. Shaft 142 engages a rack, not illustrated, which is mounted similarly and which transmits the driving force of cylinder 130 to the far side of wiping roll 120, permitting its synchronous and equal adjustment.

Surplus coating material is scraped from wiping roll 120 by means of a blade 154. This comprises a spring steel blade adjustably mounted on brackets 156 by means of screws 158. By controlling the position of the blade relative to the roll, the quantity of liquid coating material carried by the latter may be adjusted within predetermined limits.

Coating material removed by blade 154 is collected in an underlying pan 146, FIG. 1. The pan is supported on bars 148 connected to slides 126. Accordingly the pan moves upwardly and downwardly with roll 120. It normally is maintained in dipping relation with roll 120, to insure that the surface of the latter will remain moist at all times. It is drained through an overflow pipe 152.

As is apparent from a consideration of F IG. 1, pressure rolls 28 and coating rolls 32 all are driven in the feed direction. Wiping roll 120, however, is driven in the reverse direction. The drive by means of which this is accomplished is illustrated in FIG. 3.

A variable speed motor 160 drives a transfer shaft 162 journaled in bearings 164. A first drive chain 166 with associated sprockets drives pressure roll 28 which cooperates with roll 120. A second drive chain 170 with associated sprockets drives the remaining two rolls 28 as well as their cooperating coating rolls 32. A third drive chain 174 with associated sprockets drives doctor roll 82.

Wiping roll 120, however, is driven reversely by a separate drive. It is coupled directly to a variable speed motor 180, FIG. 2.

OPERATION The operation of the herein described panel coating apparatus is as follows:

When all three of coating sub-assemblies 18, 20, 22 are in their operating position, panel 16 is guided by guides 24 successively between the roll pairs. The roll pair of sub-assembly l8 floods the under surface of the panel with coating material. The roll pair of subassembly l8 floods the under surface of the panel with coating material. The roll pair of sub-assembly applied further coating and also controls the amount of coating material applied. Both roll pairs drive the panels through the roll pair sub-assembly 22, being assisted by the pressure roll 28 of the latter, which rotates in the feed direction.

However, wiping roll 120 rotates in a reverse direction. it wipes the under surfaces of the panels and provides a final control of the amount and distribution of coating material applied thereto. lts wiping action, for example, may remove much of the coating material from the elevated areas of embossed surfaces, leaving a proportion of the coating material in the depressed areas thereof and imparting a finished appearance to the panels.

Depending upon such factors as the surface of the panels, embossed or plain; the quality of the panels; the composition of the panels; and the identity of the coating material applied; one or more of the coating sub-assemblies may be removed from, or placed into, operative positions. Thus the coating rolls of one or the other of sub-assemblies 18, 20 may be adjusted by the use of crank 77. Wiping roll may be adjusted by operation of cylinder and associated rack and pinion system 136. This lends operating versatility to the assembly.

In all cases, the apparatus is applicable to the coating of panels at a very high production rate, i.e., at a rate of several thousand panels per day. Since the coating is applied to the under surfaces of the panels, they are free from dust and trash material, eliminating blemishes attributable to such sources. Also, any excess paint or other coating material which may be applied drips down into the underlying pans. This avoids smearing of the coated surface and contributes further to the overall high quality of the coated panels obtained by operation of the apparatus.

Having thus described our invention in preferred embodiments, we claim as new and desire to protect by letters patent:

1. Roll coating apparatus for panel products comprising:

a. coating applying means arranged for applying coating material to the underside of a horizontally positioned panel,

b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising 1. an upper pressure roll,

2. a lower wiping roll,

3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, the mounting means comprising a pair of slides positioned one on each end of the wiping roll and mounting the same, a pair of vertically arranged guideways each receiving one of the slides, a fluid operated cylinder connected to one of the slides for adjusting it in a vertical plane, and rack and pinion means interconnecting said one of said guides and the other of the slides for adjusting in unison the vertical position of the two slides, for adjusting the wiping roll between an elevated position wherein it lies in operative relation to the pressure roll and a retracted, inoperative position, and

. wiping roll drive means connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction, and

c. panel feed means arranged for driving the panel successively above and across the coating means and through the coating material distributing means.

2. Roll coating apparatus for panel products comprising:

a. coating applying means arranged for applying coating material to the underside of a horizontally positioned panel,

b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising 1 an upper pressure roll,

2. a lower wiping roll,

3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, and

4. wiping roll drive mans connected to the wiping b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising roll for reversely rotating it in a direction op- 1. an upper pressure roll, posed to the panel feed direction, 2 a lower i i ll,

- Panel feed means arranged t: 8 the Panel 3. mounting means mounting the rolls rotatably in successively above and across e Coating means axially aligned cooperating relation a predeterand ihrolgh the coating material distributing mined distance from each other, the mounting means, means comprising adjustable mounting means 312218gs fizl igrfid 2 5:33]? 3: for adjusting the wiping roll between an elevated position wherein it lies in operative relation to $255? fg gzg' zgzi gi saggi g 25: 2:: the pressure roll and a retracted, inoperative position, the mounting means also mounting a scra in means, the W] in roll mountm means also m unting the pan in position whe ein the collecting posmonyhqem i y i under-surface of the wiping roll dips into liquid face i P f hqu'd coam'g materi containe mt epan, coatln material contained in the an, the WI ll'l roll m unting means being adjustasle to move thg 5"? roll means cminqcmdso the mpmg r0 or reverse y rotating it in a irection op- 35:22.?) 11'0" toward and away from the upper pres posed to the panel feed direction and 3. Roll coating apparatus for panel products companel f means arranged for panel prising: successively above and across the coating means a coating applying means arranged for applying and through the coating material distributing coating material to the underside of a horizontally meanspositioned panel, 

1. Roll coating apparatus for panel products comprising: a. coating applying means arranged for applying coating material to the underside of a horizontally positioned panel, b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising
 1. an upper pressure roll,
 2. a lower wiping roll,
 3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, the mounting means comprising a pair of slides positioned one on each end of the wiping roll and mounting the same, a pair of vertically arranged guideways each receiving one of the slides, a fluid operated cylinder connected to one of the slides for adjusting it in a vertical plane, and rack and pinion means interconnecting said one of said guides and the other of the slides for adjusting in unison the vertical position of the two slides, for adjusting the wiping roll between an elevated position whereIn it lies in operative relation to the pressure roll and a retracted, inoperative position, and
 4. wiping roll drive means connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction, and c. panel feed means arranged for driving the panel successively above and across the coating means and through the coating material distributing means.
 2. a lower wiping roll,
 2. Roll coating apparatus for panel products comprising: a. coating applying means arranged for applying coating material to the underside of a horizontally positioned panel, b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising
 2. a lower wiping roll,
 2. a lower wiping roll,
 3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, the mounting means comprising adjustable mounting means for adjusting the wiping roll between an elevated position wherein it lies in operative relation to the pressure roll and a retracted, inoperative position, the mounting means also mounting a collecting pan in position wherein the undersurface of the wiping roll dips into liquid coating material contained in the pan,
 3. Roll coating apparatus for panel products comprising: a. coating applying means arranged for applying coating material to the underside of a horizontally positioned panel, b. coating material distributing means for distributing the coating material across the panel surface and wiping excess coating material therefrom, the coating material distributing means comprising
 3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, and
 3. mounting means mounting the rolls rotatably in axially aligned cooperating relation a predetermined distance from each other, the mounting means comprising a pair of slides positioned one on each end of the wiping roll and mounting the same, a pair of vertically arranged guideways each receiving one of the slides, a fluid operated cylinder connected to one of the slides for adjusting it in a vertical plane, and rack and pinion means interconnecting said one of said guides and the other of the slides for adjusting in unison the vertical position of the two slides, for adjusting the wiping roll between an elevated position whereIn it lies in operative relation to the pressure roll and a retracted, inoperative position, and
 4. wiping roll drive means connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction, and c. panel feed means arranged for driving the panel successively above and across the coating means and through the coating material distributing means.
 4. wiping roll drive mans connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction, c. panel feed means arranged for driving the panel successively above and across the coating means and through the coating material distributing means, and d. scraping means for scraping excess coating material from the wiping roll and a collecting pan arranged for gravitationally collecting coating material removed from the wiping roll by the scraping means, the wiping roll mounting means also mounting the pan in position wherein the under-surface of the wiping roll dips into liquid coating material contained in the pan, the wiping roll mounting means being adjustable to move the wiping roll toward and away from the upper pressure roll.
 4. wiping roll drive means connected to the wiping roll for reversely rotating it in a direction opposed to the panel feed direction, and c. panel feed means arranged for driving the panel successively above and across the coating means and through the coating material distributing means. 